Method for determining governor gains for a fuel control system

• US 6,133,643 A
• Filed: 10/07/1997
• Issued: 10/17/2000
• Est. Priority Date: 10/07/1997
• Status: Expired due to Fees

• Current Assignee: Caterpillar Incorporated
• Original Assignee: Caterpillar Incorporated
• Inventors: Schmidt, Larry E., Lukich, Michael S.
• Primary Examiner(s): ENAD, ELVIN GENARGUE
• Application Number:
  US08/946,437
• Time in Patent Office: 1,106 Days
• Field of Search: 290/40 A, 290/40 B, 290/40 C, 290/40 R, 123/501, 123/527, 123/357, 123/358, 60/931, 60/433
• US Class Current: 290/40.00A
• CPC Class Codes: B60K 31/00 Vehicle fittings, acting on a single sub-unit only, for automatically controlling vehicle speed, i.e. preventing speed from exceeding an arbitrarily established velocity or maintaining speed at a particular velocity, as selected by the vehicle operator fittings acting on two or more sub-units B60W30/14; speedometers G01P; systems or devices for controlling speed in general G05D13/00 ; in traffic anti-collision system for road vehicles G08G1/16
• CPC Class Codes: B60W 10/06 including control of combustion engines
• CPC Class Codes: B60W 10/10 including control of change-speed gearings
• CPC Class Codes: B60W 2050/0011 Proportional Integral Differential [PID] controller
• CPC Class Codes: B60W 2050/0012 Feedforward or open loop systems
• CPC Class Codes: B60W 2510/0638 Engine speed
• CPC Class Codes: B60W 30/188 Controlling power parameters of the driveline, e.g. determining the required power
• CPC Class Codes: F02D 2041/1409 using at least a proportional, integral or derivative controller
• CPC Class Codes: F02D 2041/1422 Variable gain or coefficients
• CPC Class Codes: F02D 31/007 controlling fuel supply

Abstract

The present invention is adapted to provide a method for dynamically determining optimal governor dynamics, i.e., gains, for a fuel control system supplying fuel to an engine. The method determines a mode of the engine, then determines the governor gain in response to the engine mode. The mode or condition of the engine includes a transmission mode, a throttle mode, and a cruise control mode. The governor gains are determined by determining the current engine mode, selecting the appropriate gain look-up table in response to the engine mode, and responsively selecting a gain value from the look-up table in response to at least one of the desired and actual speed. The gain maps are determined using empirical data and classical control system design methods, and storing the results in gain maps, or tables. The governor gain values are used in a forward and a feedback path PID control algorithm. The forward path PID control algorithm determines a fuel command in response to at least one of the desired engine speed, and modified actual engine speed, and the governor gain values. The feedback path PID control algorithm determines a modified actual speed in response to at least one of the desired and actual speeds, and the appropriate governor gain values.

Claims

1. A method for dynamically determining a governor gain for a control algorithm of a fuel control system having a forward control algorithm, a feedback control algorithm, and an engine, comprising the steps of:

determining an engine mode;

sensing a desired speed of said engine and responsively generating a desired speed signal;

sensing an actual speed of said engine and responsively generating an actual speed signal;

storing a forward governor gain look-up table for each engine mode, said look-up tables corresponding to a plurality of said desired speeds and modified actual engine speeds;

storing a feedback governor gain look-up table for each engine mode, said look-up tables corresponding to a plurality of said desired and actual engine speeds;

receiving said desired and actual speed signals and selecting a feedback governor gain look-up table in response to said engine mode, and selecting said feedback gain value from said feedback governor gain look-up table in response to said desired and actual speed signals, determining a modified actual speed in response to said feedback gain value, and generating a modified actual speed signal; and

,

receiving at least one of said desired and modified actual speed signals and selecting a forward governor gain look-up table in response to said engine mode, and selecting said forward gain value from said forward governor gain look- up table in response to said desired and modified actual speed signals, determining a fuel command in response to said forward gain value, and delivering said fuel command to said engine.

2. A method for dynamically determining a governor gain for a control algorithm of a fuel control system having a forward control algorithm, a feedback control algorithm, and an engine, comprising the steps of:

determining an engine mode is one of a cruise control mode, a throttle mode, and a transmission shift mode;

sensing a desired speed of said engine and responsively generating a desired speed signal;

sensing an actual speed of said engine and responsively generating an actual speed signal;

sensing a load of said engine and responsively generating a load signal;

storing a forward governor gain look-up table for each engine mode, said look-up tables corresponding to a plurality of said desired speeds and a modified actual engine speeds, and said engine load;

storing a feedback governor gain look-up table for each engine mode, said look-up tables corresponding to a plurality of said desired and actual engine speeds, and said engine load;

receiving said desired and actual speed signals, and said load signal, and selecting a feedback governor gain look- up table in response to said engine mode, and selecting said feedback gain value from said feedback governor gain look-up table in response to said load signal, and said desired and actual speed signals, determining a modified actual speed in response to said feedback gain value, and generating a modified actual speed signal; and

,

receiving at least one of said desired and modified actual speed signals and selecting a forward governor gain look-up table in response to said engine mode, and selecting said forward gain value from said forward governor gain look- up table in response to said load, said desired and modified actual speed signals, determining a fuel command in response to said forward gain value, and delivering said fuel command to said engine.

3. A method of dynamically determining a governor gain for a control algorithm of a fuel control system having a forward control algorithm, a feedback control algorithm, and an engine, comprising the steps of;

determining an engine mode;

establishing a desired speed of said engine;

sensing an actual speed of said engine;

determining a feedback governor gain value in response to said engine mode, and at least one of said desired speed and said actual speed;

modifying said sensed actual speed in response to said feedback gain value;

determining a forward gain value in response to said engine mode, and at least one of said desired speed and said modified actual speed; and

,

determining a fuel command in response to said forward gain value, and delivering said fuel command to said engine.

4. A method, as set forth in claim 3, wherein the step of determining a feedback governor gain value further comprises the steps of:

selecting a feedback governor gain look-up table in response to said engine mode, said look-up table corresponding to a plurality of desired and actual engine speeds; and

,

selecting said feedback gain value from said feedback governor gain look-up table in response to at least one of said desired and actual speeds.

5. A method, as set forth in claim 3, wherein the step of determining a feedback governor gain value further comprises the step of selecting said feedback gain value from a feedback governor gain look-up table in response to said engine mode and at least one of said desired and actual speeds.

6. A method, as set forth in claim 4, wherein the step of determining a forward gain value further comprises the steps of:

selecting a forward governor gain look-up table in response to said engine mode, said look-up table corresponding to a plurality of desired and actual engine speeds; and

,

selecting a forward gain value from said forward governor gain look-up table in response to at least one of said desired and modified actual speed signals.

7. A method, as set forth in claim 5, wherein the step of determining a feedback gain value further comprises the step of selecting a feedback gain value from a feedback governor gain look-up table in response to said engine mode and at least one of said desired and modified actual speed signals.

8. A method, as set forth in claim 6, further comprising the step of determining a load of said engine.

9. A method, as set forth in claim 8, wherein said forward governor gain look-up table corresponds to a plurality of desired engine speeds, actual engine speeds, and engine loads.

10. A method, as set forth in claim 9, wherein the step of selecting a forward governor gain further comprises the step of selecting a forward governor gain in response to selecting a forward gain value from said forward governor gain look-up table in response to at least one of said desired speed, said actual speed and said load.

11. A method, as set forth in claim 10, wherein said feedback governor gain look-up table corresponds to a plurality of desired engine speeds, actual engine speeds, and engine loads.

12. A method, as set forth in claim 11, wherein the step of selecting a feedback governor gain further comprises the step of selecting a feedback governor gain in response to selecting a feedback gain value from said forward governor gain look-up table in response to at least one of said desired speed, said actual speed and said load.

13. An apparatus adapted to control an engine, comprising:

an actual speed sensor adapted to sense a parameter indicative of an actual speed of said engine and responsively generate an actual speed signal;

a desired speed indicator adapted to sense a parameter indicative of a desired speed of said engine and responsively generate a desired speed signal; and

,

a microprocessor adapted to receive said actual speed signal and said desired speed signal, establish a mode of said engine, determine a feedback governor gain value in response to said engine mode and at least one of said desired speed and said actual speed, modify said actual speed signal in response to said feedback gain value, determine a forward gain value in response to said engine mode, and at least one of said desired speed and said modified actual speed, determine a fuel command in response to said forward gain value, and deliver said fuel command to said engine.

14. An apparatus, as set forth in claim 13, wherein said microprocessor is further adapted to select a feedback governor gain look-up table in response to said engine mode, said look-up table corresponding to a plurality of desired and actual engine speeds, and select a feedback gain value from said feedback governor gain look-up table in response to at least one of said desired speed signal and said actual speed signal.

15. An apparatus, as set forth in claim 14, wherein the microprocessor is further adapted to select a forward governor gain look-up table in response to said engine mode, said look-up table corresponding to a plurality of desired and actual engine speeds, and select a forward gain value from said forward governor gain look-up table in response to at least one of said desired speed signal and said modified actual speed signal.

16. A method of dynamically determining a governor gain for a control algorithm of a fuel control system having a forward control algorithm, a feedback control algorithm, and an engine, comprising the steps of:

determining an engine mode;

establishing a desired speed of said engine;

sensing an actual speed of said engine;

determining a feedback governor gain value in response to said engine mode, and at least one of said desired speed and said actual speed;

modifying said sensed actual speed in response to said feedback gain value;

determining a forward gain value in response to said engine mode, and at least one of said desired speed and said modified actual speed, said forward gain value being located on a forward governor gain look-up table corresponding to a plurality of desired and actual engine speeds; and

, determining a fuel command in response to said forward gain value, and delivering said fuel command to said engine.